Alex Smith is entering his second season with the Chiefs. / Denny Medley, USA TODAY Sports

by Tom Pelissero, USA TODAY Sports

by Tom Pelissero, USA TODAY Sports

The team announced Sunday night it has signed Alex Smith to a long-term contract extension, which a person with knowledge of the deal told USA TODAY Sports is for four years and $68 million, including $45 million in guarantees.

The person spoke on condition of anonymity because details were to remain private on the contract, which was first reported by ESPN.

Smith, 30, was entering the last year of the three-year deal he signed in 2012 with the San Francisco 49ers, who traded him to the Chiefs last year.

In his first season in coach Andy Reid's offense, Smith set career highs in touchdown passes (23) and passing yards (3,313) over 15 regular-season starts, helping the Chiefs make the playoffs.

In and out of the lineup and different offenses during his eight seasons with the 49ers, Smith told USA TODAY Sports at training camp this month his focus was to sign a deal he'd play out - not the type of pay-as-you go pacts signed in recent months by Colin Kaepernick and Andy Dalton.

The full breakdown of Smith's new deal wasn't immediately available. But general manager John Dorsey's statement on the deal indicated he expects it will keep Smith around for a while.

"It was a priority of ours to get this deal done and keep Alex in a Chiefs uniform long-term," Dorsey said in a statement issued by the team. "Alex is a proven leader on and off the field. He is a special individual with a lot of ability, and we are fortunate to have him here."